Cellulose-acetate film composition



Patented Feb. 9, 1926.

UNITED STATES PATENT OFFICE.

STEWART J'. CARROLL, OF ROCHESTER. NEW YORK ASSIGNOR TO EASTMAN KODAK COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION 01 NEW YORK.

GELLULOSE-ACETATE rILiu oomrosrrxon.

No Drawing.

To all wizom it may concern:

Be it known that I, STEWART J. Cannonn, a citizen of the United States of America, lesiding at Rochester, in the county of Monroe and State of New York, have invented certain new and useful Improvements in Cellulose-Acetate Film Compositions, of which the following is a full, clear, and exact specification.

This invention relates to cellulose acetate compositions for making films and relates also to films embodying such compositions. One object of my invention is to provide a cellulose acetate composition which is flowable and may be made by the usual methods into permanently transparent and strong sheets or films of the desired thinness that will maintain their flexibility under adverse conditions, that are substantially waterproof or unaffected by ordinary photographic fluids, and possess the other desired properties for a support for sensitive photographic coatings. Another object of my invention is to provide a film having such qualities from such a flowable composition. Other objects will hereinafter appear.

I have found that a film-forming cellulose acetate composition. having the above mentioned desirable qualities can be obtained by mixing cellulose acetate, preferably the acetone-soluble species, with tributyrin in certain proportions, a common solvent such as acetone being employed to make the composition properly flowable in the usualprocesses of making films. I have also found that a film made from such a properly proportioned composition not only exhibits transparency, strength, resistance to photo graphic liquids, etc., but likwise has a remarkable resistance to conditions which ordinarily cause'brittleness in cellulose acetate film. Films embodying my invention will retain useful flexibility even when exposed for more than a month to incubation at C. While I shall now describe one form of my invention by way of example,

' it will be understood that I am not restricted Application filed April 22, 1925. Serial No. 25,144.-

thereto, except as indicated in the appended claims.

By way of illustration I dissolve 100 parts of acetone-soluble cellulose acetate in 300 I to 500 (say 400) parts of acetone along with 10 to 35 parts by weight of tributyrin. 30 parts of trihutyrin in said formula are especlally efl'ective. permitting transparency and at the same time insuring flexibility.

I prefer to use tributyrin which is substantially free from dibutyrin and monobutyrln, but these lower esters may be mixed with the tributyrin without harm up to the point where they render the mixture too hygroscoplc.

The solutions given in the above illustration are sufliciently viscous and yet flowable to be used in the usual processes of film manufacture. the acetone volatilizing, but not too rapidly to impair the product.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A flowable film-forming composition comprising 100 parts by weight of cellulose acetate, from 10 to 35 parts by weight of tributyrin, and sufficient solvent common to said ingredients to render the composition flowable.

2. A flowable film-forming composition of matter comprising 100 parts by Weight of acetone-soluble cellulose acetate, 30 parts of.

3. As an article of manufacture a transparent film comp-rising cellulose acetate and suflicient tributyrin to maintain flexibility therein after prolonged heating at 65 C.

4. A transparent film which remains flexible after heating for more than a month at 65 G., comprising parts by weight of acetone-soluble cellulose acetate and from 10 to 35 parts by weight of tributyrin.

Signed at Rochester, New York, this 10 day of April, 1925.

STEWART J. CARROLL. 

